Firing mechanism



2 Sheets-Sheet l G. M. MOCANN FIRING MECHANISM Filed June 19. 1929 M am 53 h I l March 18, 1930.

March 18, 1930. M. ,McCANN FIRING MECHANISM Filed June 19, 1929 2 Sheets-Sheet 2 FT E . gm'ntoc George I"I-M'='Eanri Patented Mar. 18, 1930 PATENT @FFECE GEORGE M. MCCANN, OF NEW CASTLE, DELAWARE FIRING MECHANISM Application filed June 19, 1929.

Serial No. 372,059.

(GRANTED UNDER THE ACT OF MARCH 3, 1883, AS AMENDED APRIL 30, 1928; 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The subject of this invention is a firing mechanism particularly designed as an improvement for the type of mechanism originating in Patent No. 710,124 of 1902.

This inventionrelates specifically to that type of firing mechanism in which an actuator, a firing pin and a spring are arranged so that the firing movement of the actuator energizes the spring and then releases the firing pin to be driven home by the spring. When the force thus applied to the actuator is removed, the rearward action of the spring, being directly applied to the actuator through a leverage which is greater than the indirect application thereto through the firing pin of the forward action of the spring, produces retraction of the mechanism to cocked position and retention in this position.

The improvements of this application are directed to a provision whereby the firing pin spring is inoperated to enable the firing pin to complete its movement to firing position through its own inertia and to have a corresponding unrestrained retraction when a cartridge case is moved across the face of the breech block during ejection. The purpose in thus disconnecting the firing pin from its spring is to prevent damage to the pin caused by the practice of the operator of holding on to the lanyard during recoil and counter-recoil of the gun and thereby maintaining the firing pin spring in compression.

WVith the foregoing and other objects in View, the invention resides in the novel arrangement and combination of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed may be made within the scope of what is claimed without departing from the spirit of the invention.

A practical embodiment of the invention is illustrated in the accompanying drawings, wherein:

Fig. 1 is a longitudinal sectional view through the improved firing mechanism showing the parts in the cocked position;

Fig. 2 is a similar view showing the parts in firing position;

Figs. 3 and 4 are fragmentary longitudinal sectional views taken at right angles respec tively to Figs. 1 and 2;

Fig. 5 is a view in rear elevation of the firing pin collar;

Fig. 6 is a longitudinal sectional view thereof;

Fig. 7 is a plan view thereof.

Referring to the drawings by numerals of reference:

A breech block 5 is formed with a bore 6 which is closed at the face of the block by a plug 7 having a central aperture 8. A casing 9 containing a firing mechanism is inserted into the bore from the rear of the block and retained by means of bayonet joint 10.

The firing mechanism which is housed within the casing comprises a firing pin' 11, a sleeve 12 slidable on the stem 13 of the firing pin and a spring 14, confined between the base 15 of the sleeve and a collar 16 in rear of the head 17 of the firing pin. Extension of the firing pin and sleeve is limited by a lug 18 formed on the upper rear end of the pin and projecting into the path of the sleeve.

Referring to Figs. 3 and 4, the collar 16 is formed with a number of forwardly extending keys 19, two being shown, which are movable in key-ways 20 in the casing 9. The keys are of such a length that they will e11- gage and be arrested by the plug 7 while the firing pin is capable of further forward movement due to its inertia before it is likewise arrested. This additional movement, as represented by the space 21 between the members (Figs. 2 and 4:) will be in excess of the amount of projection of the point of the firing pin when in firing position. As a consequence a cartridge case 29 moving across the face of the plug 7 during ejection may cam the firing pin rearwardly to a retracted position within the plug 7 without the resistance of the spring 14 being encountered.

Mounted transversely both in the breech block 5 and easing 9 is a shaft 22 on which is fixed an arm 23 placed in line with the firing pin and bifurcated to embrace the stem thereof. The arm is in engagement through the forward face of its extremities 24 with the rear face of the sleeve 12 and it is also in engagement through an intermediate portion 25 with lugs 26 on the rear extremity of the firingpin. In this manner the rearward and forward actions of the spring are transmitted to the arm with different leverages.

The mechanism is held in the cocked position by a sear 27 journaled on the shaft 22. The sear is formed with a cam face 28, for engagement of the sleeve 12 when moved forwardly. The operation of the mechanism conforms to that described in the patent, previously referred to in which the actuator is considered as composed of the sleeve 12 and the fulcrumed arm 23. r

If the spring 14L is permitted to act on the firing pin 11 throughout its forward movement then the firing pin will be held in the extruded position during the period, either in recoil or counter-recoil, of ejectionof the empty cartridge case, whenever the operator GEORGE M. MoQANN.

forgets to releasethe lanyard by which he actuates the shaft 22 to energize the firing pin spring. By interposing the collar 16 to disconnect the spring from the firing pin during its final movement as in Figs. 2 and 4, the firing pin will be free to be cammed rearwardly by the cartridge case even when .i

the spring is energized.

I cla1m: a I 1. In a firmg mechanism, a casing, an actuator in the casing, a firing pin in the casing,

a spring seat associated with the firing pin, a spring confined between the actuator and spring seat, a stop member limiting forward movement of the firing pin, and means on the spring'seat guided by the casing and engageable with the sto 3 member to limit the forward movement 0 the spring seat short of the firing pin.

2. In a firing mechanism, a casing, anactuator in the casing, a firing pin in the casing, a spring seat associated with the firing pin, a spring confined between the actuator and spring seat, a' stop member limiting forward movement of the firing pin, and means on the spring seat engageable with the stop member to limit the forward movement of the spring seatshort of the firing pin.

3. In a firing mechanism, a casing, an actuator in the casing, a firing pin in the easing, a spring seat associated with the firing pin, a spring confined between the actuator and spring seat, a stop member limiting forward movement of the firing pin, and means engageable with the stop member to limit the forward movement of the spring seat short ofthe firing pin. 7 V

4. In a firing mechanism, a casing, an actuator in the casing, a firing pin in the easing, a spring seat associated with the firing p n, a spring confined between the actuator 

